Eating to Live OR Living to Eat !!! > Take the Quiz !

HEALTH JOURNAL
JULY 13, 2010
Eating to Live or Living to Eat?
Stomach vs. Brain: Discovering Why Some People Can Resist Dessert While
Others Can't
 Imagine the typical office birthday party.
 It's after lunch, so everybody is full. Then, in comes a luscious
 chocolate confection. The sight, the smell—even the sound of the word
 "cake!"—stimulate the reward-and-pleasure circuits of the brain,
 activating memory centers and salivary glands as well.


Melinda Beck asks the age-old question: Do you eat to live, or live to eat?

Scientists, it turns out, have learned much more about how appetite works
in the brain - and the findings have major consequences.
 Those reactions quickly drown out the subtle signals from the stomach that
 are saying, in effect, "Still digesting down here. Don't send more!"
 Social cues add pressure and permission to indulge. Soon, everybody is
 having a slice—or two.
 Scholars have understood the different motives for eating as far back as
 Socrates, who counseled, "Thou shouldst eat to live, not live to eat." But
 nowadays, scientists are using sophisticated brain-imaging technology to
 understand how the lure of delicious food can overwhelm the body's
 built-in mechanism to regulate hunger and fullness, what's called
 "hedonic" versus "homeostatic" eating.

 One thing is clear: Obese people or those with existing weight issues react much more hedonistically to sweet, fat-laden food in the pleasure and reward circuits of the brain than
 healthy-weight people do. Simply seeing pictures of tempting food can
 light up the pleasure-seeking areas of obese peoples' brains.
Two Reactions to Cake

 Two conferences on obesity  examined aspects of how
 appetite works in the brain and why some people ignore their built-in
 fullness signals.   (How many times have you said "I'm SO full and then polished off dessert ?!)  Scientists hope that breakthroughs will lead to ways to retrain people's thinking about food or weight-loss drugs that can target certain brain areas.
 In a study presented this week at the International Conference on Obesity
 in Stockholm, researchers from Columbia University in New York showed
 pictures of cake, pies, french fries and other high-calorie foods to 10
 obese women and 10 non-obese women and monitored their brain reactions on
 fMRI scans. In the obese women, the images triggered a strong response in
 the ventral tegmental area (VTA), a tiny spot in the midbrain where
 dopamine, the "desire chemical," is released. The images also activated
 the ventral pallidum, a part of the brain involved in planning to do
 something rewarding.
 "When obese people see high-calorie foods, a widespread network of brain
 areas involved in reward, attention, emotion, memory and motor planning is
 activated, and all the areas talk to each other, making it hard for them
 to resist," says lead investigator Susan Carnell, a research psychiatrist
 at the New York Obesity Research Center at Columbia University.

The Power of Cake? Take the Quiz !

 

This Power-of-Food Scale helps gauge how vulnerable you are to 'hedonic'
eating. Indicate from 1-5 which of the following best describes you:
1 Don't agree at all
2 Agree a little
3 Agree somewhat
4 Agree
5 Strongly agree

___ 1. I find myself thinking about food even when I'm not physically
hungry.
___ 2. I get more pleasure from eating than I do from almost anything else.
___ 3. If I see or smell a food I like, I get a powerful urge to have some.
___ 4. When I'm around a fattening food I love, it's hard to stop myself
from at least tasting it.
___ 5. It's scary to think of the power that food has over me.
___ 6. When I know a delicious food is available, I can't help myself from
thinking about having some.
___ 7. I love the taste of certain foods so much that I can't avoid eating
them even if they're bad for me.
___ 8. Just before I taste a favorite food, I feel intense anticipation.
___ 9. When I eat delicious food I focus a lot on how good it tastes.
___ 10. Sometimes, when I'm doing everyday activities, I get an urge to eat
"out of the blue" (for no apparent reason).
___ 11. I think I enjoy eating a lot more than most other people.
___ 12. Hearing someone describe a great meal makes me really want to have
something to eat.
___ 13. It seems like I have food on my mind a lot.
___ 14. It's very important to me that the foods I eat are as delicious as
possible.
___ 15. Before I eat a favorite food my mouth tends to flood with saliva.
Scoring: Add up your responses and divide the total by 15.
1.0 - 2.3: You're unlikely to be preoccupied with food or lose control over
eating.
2.4 - 3.6: You're somewhat preoccupied with food but are unlikely to have a
problem unless you're significantly overweight.
3.7 - 5.0: You're frequently preoccupied with food and at risk of losing
control over your eating. This is especially problematic if you are also
significantly overweight.

 Similar brain reactions occurred in the obese subjects even when
 researchers merely said the words "chocolate brownie"—but not when they
 saw or heard about lower calorie foods such as cabbage and zucchini.
 Reactions were far less pronounced in the non-obese subjects.
 More such studies are being presented in Pittsburgh this week at the
 annual meeting of the Society for the Study of Ingestive Behavior. In one,
 neuroscientists from Yale University's John B. Pierce Laboratory had 13
 overweight and 13 normal-weight subjects smell and taste chocolate or
 strawberry milkshakes and observed their brains with fMRI scans.
 The overweight subjects had strong reactions to the food in the
 amygdala—the emotional center of the brain—whether they were hungry or
 not. The healthy-weight subjects showed an amygdala response only when
 they were hungry.
 "If you are of normal weight, your homeostatic mechanisms are functioning
 and controlling this region of the brain," says lead investigator Dana
 Small. "But in the overweight group, there is some sort of dysfunction in
 the homeostatic signal so that even though they weren't hungry, they were
 vulnerable to these external eating cues."
 Studies have found that a diet of sweet, high-fat foods can indeed blunt
 the body's built-in fullness signals. Most of them emanate from the
 digestive tract, which releases chemical messengers including
 cholecystokinin, glucagon-like peptide and peptide YY when the stomach and
 intestines are full. Those signals travel up to the brain stem and then
 the hypothalamus, telling the body to stop eating.
 Obesity also throws off the action of leptin, a hormone secreted by fat
 tissue that tells the hypothalamus how much energy the body has stored.
 Leptin should act as a brake against overeating, and it does in
 normal-weight people. But most obese people have an overabundance of
 leptin, and somehow their brains are ignoring the signal.
 All these findings beg the question, which came first? Does obesity
 disrupt the action of leptin, or does a malfunction in leptin signaling
 make people obese?
 Similarly, are some people obese because their brains overreact to
 tempting food, or do their brains react that way because something else is
 driving them to overeat? Researchers at Yale and elsewhere are turning to
 such questions next. "It's possible that these changes reflect how the
 brain has adapted to eating patterns in obese people, and that could
 create a vicious circle, putting them at risk for even more disordered
 eating," says Dr. Small.
 There are plenty of other metabolic mysteries, too: Why are some "foodies"
 who get intense pleasure from eating able to stop when they're full and
 others aren't? Is the tendency to eat way past fullness genetic or learned
 behavior, and how much can it be changed?
 The answers are still elusive, but neuroscientists and behavioral experts
 are finding some tantalizing clues.
 Some fMRI studies have found that while tempting food stimulates the
 release of dopamine in obese people, they actually have fewer dopamine
 receptors than normal weight subjects do, so they may derive less pleasure
 from actually eating, setting up a craving for more.

 Curiously, several studies have shown that some forms of gastric bypass
 surgery can actually create changes in the brains of formerly obese people
 —and not just because their stomachs are smaller and fill up more quickly.
 Levels of leptin and glucose tend to drop in bypass patients, ending
 diabetes for many of them. PET scans also show that bypass patients have
 more dopamine circulating in their brains, which may help control appetite
 as well.
 Some of the most intriguing imaging studies have peered into the brains of
 people who have lost significant weight and kept it off through diet and
 exercise alone—although researchers say they're hard to find.
 "They are very controlled individuals, and they are very rare. We had to
 fly some in from Alaska," says Angelo Del Parigi, a neuroimaging
 scientists who finally located 11 "post-obese" subjects who had dieted
 down to the lean range. In his studies for the National Institutes of
 Health's diabetes research center in Phoenix, Dr. Del Parigi found that
 food still elicited strong responses in the middle insula and the
 hippocampus, brain areas involving addiction, reward, learning and memory,
 just like the 23 obese subjects did.
 "The only way they have to counteract these strong predispositions
 is by having a very controlled lifestyle, with restrained food intake and
 exercise." He and his colleagues at the NIH have observed that in PET scans, too. In
 another study, 17 people who had successfully lost weight had more
 activity in the dorsal lateral prefrontal cortex, a part of the brain
 involved in impulse-control in response to food than people who were still
 obese.
 In short, successful weight losers seemed to have having second thoughts
 about eating on impulse, says Dr. Del Parigi. "These people see a piece of
 pie that is very inviting, but they think, 'No, I have to diet. Otherwise,
 I will become obese again. I will suppress that pleasure,' " he says.